1. Field of the Invention
The present invention relates to a control apparatus for a variable valve apparatus which varies an operating characteristic of an engine valve in an internal combustion engine, and a method thereof.
2. Description of the Related Art
Japanese Unexamined Patent Publication No. 2001-254637 discloses an apparatus for diagnosing the malfunction of a variable valve lift apparatus which varies a lift amount of an engine valve.
In the above diagnosis apparatus, it is judged that the variable valve lift apparatus is malfunctioned, when a change in lift amount of the engine valve is equal to or smaller than a predetermined value and also when an absolute value of the deviation between the lift amount of the engine valve and a target value thereof exceeds a predetermined value.
If a control unit that controls the variable valve lift apparatus is operated normally, it is possible to execute the fail-safe processing when the variable valve lift apparatus is malfunctioned.
However, in the above diagnosis apparatus, there has been a problem in that the fail-safe processing cannot be executed if the control unit is failed.